YASKAWA LA500, Technical Manual

Page: 65 / 376

Electrical
Installation
3
3.8 Braking Resistor Installation
YASKAWA SIEPYEULA5001C LA500 Technical Manual 65
3.8 Braking Resistor Installation
A braking resistor or braking resistor unit (dynamic braking option) helps stop the motor quickly and smoothly
when there is high load inertia. If you try to decelerate a motor in less time than usual for a coast to stop, the
motor will rotate faster than the synchronous speed that aligns with the set frequency. This will cause the motor to
become an induction generator. The inertia energy of the motor and regenerate to the drive and charge the drive
DC bus capacitor and increase the voltage. If the voltage is more than the overvoltage level, an
ov [Overvoltage]
will occur. To prevent these overvoltage faults, a dynamic braking option is necessary.
WARNING!
Set L3-04 = 0 [Stall Prevention during Decel = Disabled] when you operate the drive with:
• a regenerative converter
• regenerative unit
• braking resistor
• braking resistor unit.
If you set the parameter incorrectly, the drive can decelerate for too long and cause serious injury or death.
NOTICE: Damage to Equipment. Before you connect a dynamic braking option to the drive, make sure that qualified personnel
read and obey the Braking Unit and Braking Resistor Unit Installation Manual (TOBPC72060001). If you do not read and obey
the manual or if personnel are not qualified, it can cause damage to the drive and braking circuit.
Note:
Select the correct braking circuit size to dissipate the power that is necessary to decelerate the load in the correct time. Before you run
the drive, make sure that the braking circuit can dissipate the energy for the set deceleration time.
WARNING! Fire Hazard. Do not connect a braking resistor to ter1 or -. Use terminals B1 and B2 for the braking resistor
connections. If you connect a braking resistor to the incorrect terminals, it can cause damage to the drive and braking circuit and
serious injury or death.
NOTICE: Connect braking resistors to the drive as shown in the connection diagram examples. If you wire the braking circuits
incorrectly, it can cause damage to the drive or equipment.
◆
Install a Braking Resistor
Connect the braking resistor to a drive as shown in Figure 3.30 .
Figure 3.30 Install a Braking Resistor
◆
Dynamic Braking Option Overload Protection
To prevent overheating the dynamic braking option, set a sequence to de-energize the drive at the trip contacts of
the thermal overload relay.
Figure 3.31 Power Supply Interrupt for Overheat Protection Example